In recent years greater attention has been paid to protecting the user of a hand-held chain saw from vibration generated by the chain saw. In a chain saw powered by an internal combustion engine --commonly a single cylinder two-stroke cycle engine-- the engine is a primary source of vibration. In order to protect the user from such vibration means is provided for isolating the engine from a unit comprising the fuel tank, oil tank and handles by which the chain saw is held.
A further source of vibration and noise is the chain and guide bar assembly comprising the guide bar, the cutting chain which runs on the guide bar and the sprocket by which the chain is driven. As the chain is driven at high speed by the drive sprocket, a considerable amount of noise and vibration are generated by engagement of the sprocket teeth with the chain, by the chain running on the guide bar and around the nose of the guide bar which may or may not be provided with a nose sprocket or roller and by engagement of the teeth of the chain in rapid succession with the work.
Heretofore the guide bar has been mounted rigidly on the power head of the chain saw, for example by being bolted together with a drive case cover onto the engine casing. By reason of this rigid mounting, vibration and noise generated in the guide bar assembly is transmitted to the powerhead of the chain saw which tends to amplify the vibration and noise in somewhat the same manner as the shell of a violin. The vibration and noise of the guide bar assembly as thus amplified contributes in a significant way to the overall vibration problem. However, heretofore little or no attention has been paid to elimination or reduction of guide bar vibration and noise.
The problem of dealing with vibration and noise generated in the guide bar assembly is rendered more difficult by the fact that the guide bar needs to be connected with the powerhead in such manner that the operator has effective control of the cutting of the chain saw. Since the guide bar and chain running thereon constitute the cutting element of the chain saw, the operator needs to be able to control accurately the position and angle of the guide bar in order to cut at the location and in the direction desired. If the interconnection between the guide bar and the handles on the powerhead were too "soft" the operator would not have adequate control of the cutting operation.